A conventional load cell of the parallel beam type is generally formed from an unitary block of aluminum, machined to provide a pair of parallel flexures and an intermediate sensing beam secured within the block. A strain gage is secured on the sensing beam to produce an electrical signal responsive to the magnitude of load imposed on a platter secured on one end of the load cell. Another conventional type of load cell eliminates the sensing beam entirely and secures the strain gage on one of the flexures.
One problem encountered with conventional load cells of the above type is that they are designed without overload or underload protection. Overloading of the load cell, for example, can result in permanent deformation of the flexures and sensing beams resulting in its loss of structural integrity and usability. Thus, the load cell must be discarded and replaced by a new one.
A further problem encountered with conventional load cells is that moment adjustment for offset loading is solely accomplished by machining critical areas of the load cell in the area of its flexures. Over-machining, causing removal of too much load cell material at such critical areas, will also result in a load cell that is rendered unusable and that must be discarded. The term "moment adjustment" offset loading adjustment relates to the calibration of the load cell to achieve the same weight readout of the load independent of its position on the platter.